The present invention relates generally to power cord retention devices and more particularly to a power cord retention device for a portable AC powered tool.
Many power tools require an extension power cord to connect the power tool to an AC power source. Portable AC powered tools such as hedge trimmers or string trimmers typically have male electrical contact blades in the housing of the power tool that connect to a female electrical receptacle plug at the end of an extension power cord. A common problem with portable AC powered tools is how to secure the extension power cord to the power tool in such a manner that it will not easily pull free during operation of the power tool. This is complicated by variations in the design of power cords that make one solution for securing a power cord not necessarily practical for all power cords. Further, some power tools are often operated in a way that strains the connection between the power cord and the AC power jack of the power tool. For example, an operator can carry a hedge trimmer with the extension power cord in tow thus causing an intermittent tugging or strain to the power cord connection. As a result of both the constant vibration of the tool together with the intermittent movement of the operator, the power cord can easily pull free of the tool""s AC power jack.
Therefore, there is a need for a power cord retaining device that will operate with a variety of extension power cords and which will even more securely hold the extension cord to the power tool in spite of movement and vibration that is common in the operation of the power tool.
It is an object of the invention to provide a system for more securely holding a female plug of an extension power cord to a portable AC power tool. It is a further object to provide a system that is easily used by an operator, and which securely holds the power cord secured to the tool""s AC power jack in spite of vibration and movement of the power tool during use thereof. An additional object is to provide a cord retaining system that will work with a variety of extension power cord types including a variety of differently shaped plugs. Another object of the invention is to provide a system that is easy to use and understand by its operator and which does not require the use of external tools or fasteners to secure the plug head of an extension power cord to an AC power jack of a power tool.
The present invention is directed to a cord retaining system associated with a housing of a portable power tool. The system provides a secure connection that can be quickly and easily effected between the power tool and the power cord so that the power cord cannot be accidentally pulled free from engagement with a power jack of the tool during use of the power tool.
In operation, the female plug at one end of the power cord is secured to the body or housing of the power tool by a retaining member that pulls the plug towards the body or housing of the power tool once the plug is engaged in a mating AC power jack disposed in the housing. In one preferred form, the retaining member comprises a linearly moveable yoke adapted to engage a plug of an AC power cord. A release member engages a portion of the yoke to hold the yoke in a locking position once the yoke has secured a plug of the power cord to the power jack. The retaining yoke holds the plug securely to the power tool by a locking system that can be easily disengaged by the power tool operator when it is necessary to uncouple the power cord from the tool. Advantageously, neither engagement of the yoke to the plug head or disengagement therefrom requires the use of any external tool(s) by the operator.
The retaining system incorporates locking components with opposing surfaces that when engaged prevent movement of the yoke in one longitudinal or rotational direction. In one preferred form the yoke includes one serrated surface, and the release member, disposed in proximity to the yoke, includes a mating serrated surface. The serrated surfaces are angled such that movement in one direction is allowed while attempted movement in the opposite direction causes the teeth of the serrated surfaces to engage and prevent movement. A biasing component is used to hold the opposing serrated surfaces together, therefore allowing movement of the yoke only in the locking direction. By actuating the release member the serrated surfaces are forced apart, thus allowing the retaining yoke to move in an unlocking direction to a position allowing the operator to free the power cord from the retaining yoke and the power cord jack.
In one preferred embodiment the retaining yoke slides longitudinally within a housing of the power tool, and the yoke includes a serrated surface on a side edge thereof. A spring forces the opposing surface edge of the release member against the serrated edge of the yoke.
In a second preferred embodiment the retaining yoke slides longitudinally within the housing of the power tool and the retaining system includes a serrated surface on a top planar surface of the retaining yoke. The retaining yoke opposes a serrated surface on the release member, and a portion of the release member protrudes through a portion of the housing. The release member comprises a flexible member having a curved form. The curved form of the mechanism allows a biasing force to be exerted against the opposing serrated surface of the retaining yoke, thus preventing the yoke from moving in an unlocking direction unless the release member is engaged by the operator so as to lift it away from the serrated surface on the retaining yoke.
In a third preferred embodiment the retaining yoke rotationally moves within the housing of the power tool and comprises a rotationally moveable yoke adapted to engage a plug of the AC power cord. The retaining member has a central hub about which the retaining member moves. The central hub has a circumferentially arranged serrated surface that engages a corresponding serrated surface on a release housing portion disposed in the housing of the power tool. A compression spring in the housing portion of the cord retaining system and the hub continuously urges the serrated surface of the retaining member against the serrated surface of the release housing portion. In a locked position the retaining member engages a plug head of a power cord to retain the plug head engaged with an AC power jack in the tool housing.
To release the retaining member, a button that is attached to the hub of the retaining member is depressed. This urges the serrated surface of the retaining member away from the serrated surface on the inside of the release housing portion. The retaining member can be rotated away from the AC power jack to allow the power cord plug head to be easily removed. The orientation of the serrated surfaces allows the retaining member to only be moved toward the AC power jack if the button is not being engaged. It is only when the button is engaged that the retaining member can be rotated away from the AC power jack.
In an alternative embodiment of the retaining member the retaining yoke is slightly curved and comprises boss members that interact with the power cord plug head and aid in holding the power cord plug head in contact with the AC power jack in the power tool housing. In this embodiment the retaining yoke is particularly adapted to accommodate a variety of differing shapes and sizes of power cord plug heads. As with the third preferred embodiment, the retaining yoke moves rotationally within the housing of the power tool.
In another alternative embodiment of the retaining member the serrated surface of the retaining member and the corresponding serrated surface of the power tool housing interact to restrict but not prevent the movement of the retaining member in a direction away from the AC power jack. This alternative non-locking embodiment prevents damage to the retaining member and possibly other parts of the power cord retaining system in the event of a significant force applied against the retaining member.
In yet another preferred embodiment the power cord retaining system is provided in combination with a second cooperating retaining system. The separate retaining system comprises an opening and a hook in the power tool housing for allowing a loop of the power cord to be inserted through the opening and around the hook, thus restricting the movement of the power cord. The combined effect of the two retaining systems operating in cooperation further prevents the unintended displacement of the power cord plug from the AC power jack in the power tool housing while the power tool is in operation.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.